Microstructure and Properties of Hot Rolled Ti-23Al-17Nb Alloy Sheets

Microstructure and tensile properties of Ti-23Al-17Nb (at%) alloy sheets rolled in (α2 + B2 + O) phase field with the various heat treatments were studied. Before rolling the microstructure of the billet is B2 phase particles embedded in O phase continuity matrix. The B2 phases are deformed more greatly than α2/O phases during the same rolling step. The (α2 + B2) two-phase equiaxed microstructure can be obtained by solution treatment in (α2 + B2) phase field. The B2 phases become the continuous matrix by recrystallization and growing up of B2 and thus anisotropy caused by rolling can be decreased. The microstructure obtained by solution treatment has better tensile properties than the microstructure gained by subsequent aging treatment in (O+B2) phase field because the O phases precipitate as the block structure during aging and results in the B2 matrix continuity being broken down.